Flame retardants for polymers

ABSTRACT

1. A POLYMERIC COMPOSITION COMPRISING: (A) A POLYMER SELECTED FROM THE GROUP CONSISTING OF POLYOLEFINS, POLYAMIDES, AND POLYSTYRENES; AND (B) 0.5 TO 15 PARTS BY WEIGHT PER 100 PARTS BY WEIGHT OF SAID POLYMER OF A COMPOUND HAVING THE GENERAL FORMULA   R-O-(1,4-PHENYLENE)-C(-R&#39;&#39;)(-R&#34;)-(1,4-PHENYLENE)-O-R   WHEREIN R IS A 2,3-DIBROMO ALKYL RADICAL CONTAINING 3-10 CARBON ATOMS, AND R&#39;&#39; AND R&#39;&#39;&#39;&#39; ARE HYDROGEN OR ALKYL RADICALD HAVING 1-6 CARBON ATOMS.

nited States Patent 3,842,033 FLAME RETARDANTS FOR POLYMERS Donnie G. Brady, Ernest A. Zuech, and Roy A. Gray,

Bartlesville, 0kla., assignors to Phillips Petroleum Company, Bartlesville, Okla.

No Drawing. Continuation-impart of abandoned application Ser. No. 146,456, May 24, 1971. This application Aug. 8, 1973, Ser. No. 386,576

Int. Cl. C0815 45/46 US. Cl. 260-45.75 B Claims ABSTRACT OF THE DISCLOSURE A flame retardant for polymeric compositions which comprises a brominated 2,2-bis(4-allyloxyphenyl)propane or homologues thereof.

This application is a continuation-in-part of copending application Ser. No. 146,456, filed May 24, 1971, now abandoned.

This invention relates to flame retardants for polymers.

In one of its more specific aspects, this invention relates to brominated compounds suitable for inclusion in olefin polymers as flame retardants.

Because of the wide use of normally combustible polymers, flame retardants which act to prohibit their burning are important compounds for inclusion in polymers. This invention provides brominated compounds which are includable for this purpose in polymers of a wide variety and which are operable in the presence of a wide variety of other additives such as colorants, stabilizers, plasticizers and the like which are normally included in polymeric compositions.

According to this invention, there is provided a flame retardant for incorporation in polymeric compositions which comprises a compound having the general formula.

ill

in which each R is a brominated radical selected from the group consisting of 2,3-dibromohydrocarbyl radicals containing 3 to carbon atoms, and in which R and R" are hydrogen, alkyl, aryl and cycloalkyl radicals and combinations thereof containing up to 12 carbon atoms. Preferably, R is a 2,3-dibromo alkyl radical containing 3-10 carbon atoms, each R and R" are hydrogen or alkyl radicals having l-6 carbon atoms and the sum of all the carbon atoms in the R, R, and R" groups does not exceed 30, most preferably R and R" are said -l-6 carbon atom alkyl radicals. Among the novel compounds having this general formula is 2,2-bis[4-(2,3-dibromopropoxy)phenyl]propane.

This specific novel compound has been prepared and found to exhibit a desirable combination of properties. The organic chemist will appreciate that the terminal hydrocarbyl radicals in the molecule can be replaced by other similar hydrocarbyl radicals to produce similar compounds having similar properties. Because of ease and convenience of preparation, a preferred class of invention compounds can be represented by r r r r onz-cn-onz-o-@-e-o-onron-onz RI! wherein R and R are as previously defined.

The compounds of this invention can be effectively em ployed in many types of resins or polymers including polyolefins, polyamides, polystyrenes, and the like including polypropylene, polyethylenes, and others. The invention flame retardant additive has been specifically demonstrated to be effective in a polypropylene resin. Those skilled in the flame retardant art will conclude that the 3,842,033 Patented Oct. 15, 1974 additive can be used with advantage in other resins as well, particularly in other hydrocarbon resins such as polyethylene, polystyrene, polybutenes, polyolefin copolymers, and the like. The invention additive is presently believed to be most useful in resins comprising polymers and copolymers of polymerizable olefins including styrene.

The compounds of this invention can be employed in such compositions in the presence of antioxidants but the eflicacy of the compounds of this invention does not depend upon the inclusion of such antioxidants in the polymer. Other suitable additives can also be present in the polymer compositions. These can include fire retardant synergists such as antimony trioxide, stabilizers such as organotin carboxylates or epoxidized soybean oil, ultraviolet stabilizers, pigments, and the like.

The comopunds of this invention are incorporated in the polymeric composition in an amount within the range of about 0.5 to about 15 parts by weight per hundred parts by Weight of the resin and preferably in an amount within the range of 1-3 parts. The brominated compound can be contained in the polymeric composition in the presence of antimony oxide, the weight ratio of brominated compound to antimony oxide being from about 0.1 to 1 to about 10 to 1 with the preferred ratio being about 2 to 1.

The brominated compound can be introduced into the resin in any manner and at any stage of the formulation of the polymeric composition.

One convenient method for preparing the novel flame retardant compositions of the present invention is to contact a suitable diphenol compound with a suitable allyl halide or hydrocarbyl-substituted allyl halide under conditions of a Williamson Ether Synthesis reaction. That is, the diphenol compound, preferably in the presence of an equivalent amount of an alkali hydroxide, is contacted with the allyl halide compound and heated, preferably in the presence of a suitable solvent, at a temperature and for a time suflicient to form the corresponding diether compound. The unsaturated diether intermediate is then contacted with elemental bromine under suitable bromination conditions. Such bromination readily occurs and can be carried out at any convenient temperature, generally in a suitable solvent under conditions well known in the bromination art.

Suitable diphenol compounds are bisphenol A and compounds similar to bisphenol A. Of particular interest are diphenol compounds which can be conveniently prepared by reaction of phenol with a ketone. Thus, some suitable diphenol compounds in addition to bisphenol A are 2,2- bis(4-hydroxyphenyl)butane, 3,3 bis(4 hydroxyphenyl) hexane, and the like. Suitable allyl halide compounds are allyl chloride and homologs such as 2-butenyl chloride, 2-pentenyl bromide, S-cyclohexyl-Z-hexenyl iodide, and the like. Because compounds containing more carbon atoms than the allyl halide tend to produce significant amounts of isomers when reacted with suitable diphenol compounds, allyl halides, particularly allyl chloride, are presently preferred.

Some examples of novel flame retardant compounds which fall within the scope of the present invention are:

2,2-bis [4- (2,3-dibromopropoxy phenyl] propane 3,3-bis [4 2,3-dibromopentoxy phenyl] hexane 1-cyclohexyl-2,2-b-is [4-2, 3 -dibromoheptoxy) phenyl] butane 1, l-bis [4- 2,3-dibromopropoxy phenyl] methane 2-o-tolyl-3 ,3-bis [4- (2,3-dibromodecoxy) phenyl]pentane 13 ,13-bis[4- (2,3-dibromopropoxy)phenyl] pentacosane 2, Z-dimethyl-S ,S-bis [4- (2, 3 -dibromopropoxy phenyl] non-ane 2,2-bis [4- (2,3-dibromopropoxy phenyl] butane and the like.

3 1 Thus flame retardants of this invention can be prepared by treating 'bisphenol A with allylic halides followed by bromination. Intermediate separation of the diallyl ether prior to bromination is not required.

The following illustrates one method of preparing the 4 the two samples after various aging periods at 100 C. as a measure of flammability of the polymeric materials. Results were as follows:

compounds of this invention and their flame retardant 5 Minimal vo u oxygen effect in polymer compositions. Sample 1 Sample H EXAMPLE I iidti i 0245 0.250 To about 120 parts by weight of ethanol were added 7 days 0.242 0.188 3.6 parts by weight of sodium hydroxide. After di-ssolu- 10 5% 3g: 31; 312% tion of the sodium hydroxide, 9.1 parts by weight of bisphenol A were added; 9.4 parts by weight of allyl chloride Wem then added and the m.ixtur.e was refluxed for The above data indicate that the brominated composi- Od o ten hours after whlch was Cooled and water tion of this invention when incorporated in the polymer Washed. About 140 parts by weight of ether were added, imparted to the polymer substantially unchanging the organic layer was separated and the ether layer was ceptibflity to flammability with aging, with the polymer dried over MgSO and filtered. The ether was evaporated remaining flame retarded Over the entire aging i d, under Vacuum to yield y yP y )P P samples having test values less than 0.21 being considered Ten (10) Parts by Weight of 22'bis'(4'allyloxyphenyl) as flammable, samples having test values greater than P p We're added to about 75 Parts y Weight of 0.21 beingconsidered as flame retarded. chloroform. The resulting solution was cooled to 0 C. Th l bili t t of polymer compositions con- 042 P y Weight of Sodium carbonate Was taining the brominated compounds of this invention in- TO the mixture 3 solution of Parts y Weight of dicated that less polymer degradation occurred than in bromine in about 75 parts by weight of chloroform was compositions containing a commercially-available flame added during a period of one hour. The resulting mixture ret rdant, For example, in two comparable blends in was agitated for another hour and then washed with aquepolypropylene having a melt flow of 4.0, incorporation of ous sodium bicarbonate solution. 2,2 bis[4 (2,3 dibromopropoxy)phenyl]propane in The organic layer was dried, filtered and the liquid was amounts of 2 parts per hundred parts of resin produced evaporated under reduced pressure to leave about 20.5 compositions having melt flow values of 6.9 and 6.5, reparts by weight of a colorless oil, that slowly crystallized spectively, whereas incorporation of a commerciallyat room temperature. Upon recrystallization from etharecognized flame retardant, 2,3-dibromopropyl-2,4,6-trinol, 12 g. of a white crystalline compound were obtained. bromophenyl ether in amounts of 2 parts per hundred This material had a melting point of 75-78 C., and was parts of the same resin, produce compositions having melt analyzed as containing 40.07 wt. percent 0, 3.86 wt. perflOW Values of 209 and fespbctiybly, other Condiccnt H and 52 wt Percent Br, id tifi bl as 2 2 4 tions being identical and all melt flow values being deter- (2,3 dibromopropoxy)phenyl]propane. The infrared mined y ASTM D Condition spectrum and the nuclear magnetic resonance (NMR) EXAMPLE HI examination of the compound were ent1rely consistent 40 with the indicated structure. Some specifically confirma- Still another comparison was made which demontory items on the NMR trace were: a peak at about 7 strated the high thermal stability of polymers which conp.p.m. with a corresponding integrated area indicating tain the brominated compounds of the present invention. the presence of eight aromatic protons; a peak at about Individual samples of polypropylene of 4 melt flow con- 1.65 p.p.m. showing the presence of two methyl groups; taining 2 phr. fire-retardant additive and 1 phr. antimony a doublet at about 3.9 indicating two methylene groups trioxide were heated 10 minutes at the indicated temperaattached to oxygen atom-s; a doublet at about 4.35 repreture and then examined for color and melt flow.*

460 F. 480 F. 500 F.

Fire-retardant additive Color M.F. Color M.F. Color M.F.

Invention White 4.8 White 10.3 Ofi-white 8.7 Comparison Off-white 7.5 Light gray 13.1 Light gray 28.8

Comparison additive is senting protons on the bromine-containing carbon atom with the integrated area showing a total of six hydrogen atoms.

EXAMPLE II The 2,2-bis[4-(2,3 dibromopropoxy)phenyl]propane prepared in Example I was incorporated in polypropylene in an amount of 2 phr. (Sample I). For comparative purposes, a commercially available polymer flame retardant, 2,3-dibromopropyl-2,4,6 tribromophenyl ether was individually incorporated in a comparable polypropylene composition (Sample 11). Each composition also contained antimony trioxide in an amount of 1 phr. and a hindered phenol antioxidant in an amount of 0.3 weight percent.

The minimal volume fraction of oxygen required in an oxygen-nitrogen atmosphere to sustain burning of the polymeric composition was then determined for each of 2,2-bis[2,3,5,6-tetrabromo-4- (2,3-dibromopropoxy) phenyl] propane.

The results in the Table clearly show that the invention polymer system was more resistant to thermal discoloration than the closely related comparison material. In addition, the invention polymer system exhibited much less degradation at high temperatures as evidenced by the relatively small change in melt flow from that of the original polymer.

Although the invention polymer system shows high thermal stability with only the brominated compound and the antimony oxide present, its stability can, of course, be still further increased by the additional presence of conventional anti-oxidants and other stabilizers.

While the compounds of this invention have been illustrated in conjunction with certain materials, the use of the compounds of this invention is not to be considered as being limited thereto.

' *ASTDI D 1238-62T (Condition L).

It will be evident that various modifications can be made to the method of this invention. Such are, however, considered to be Within the scope of the invention.

What is claimed is:

1. A polymeric composition comprising:

(a) a polymer selected from the group consisting of polyolefins, polyamides, and polystyrenes; and

(b) 0.5 to 15 parts by weight per 100 parts by weight of said polymer of a compound having the general formula I II II wherein R is a 2,3-dibromo alkyl radical containing 3-10 carbon atoms, and R' and R" are hydrogen or alkyl radicals having 1-6 carbon atoms.

2. A composition according to claim 1 comprising in addition antimony oxide in a weight ratio of said compound to said antimony oxide of 0.1:1 to 1.

3. A composition according to claim 2 wherein said compound is present within the range of 1 to 3 parts by weight of said compound per 100 parts by weight of said polymer.

4. A composition according to claim 3 wherein said compound has the general formula 5. A composition according to claim 4 wherein said compound is 2,2-bis[4-(2,3-dibromopropoxy)phenyl]pro pane.

6. A composition according to claim 5 wherein said polymer is polypropylene.

7. A composition according to claim 5 wherein said polymer is a polyolefin.

8. A composition according to claim 7 wherein said compound is present in an amount within the range of 1-3 parts by weight per 10 parts by weight of said polymer.

9. A composition according to claim 8 wherein there is present in addition a hindered phenol antioxidant.

10. A composition according to claim 9 wherein the ratio of said com-pound to said antimony oxide is about 2 to 1.

References Cited UNITED STATES PATENTS 3,660,351 5/1972 Schmidt et a1 26045.85

MELVYN I. MARQUIS, Primary Examiner US. Cl. X.R.

um'rnn STATES xrmi orncn- 7 CERTIFICATE 0? common Patent No. 3,8h2 ,033 Dated: Oct. 15, 197

It is certified that error appears in the above-identified patent'and that sai Letters Patent are hereby corrected as shown below:

Column 6,1ine 10, "1of' should be mm 100 Signed and sealed this 31st day of December 1974.

(SEAL) Attest:

McCOY H. GIBSON JR. C; MARSHALL 'DANN Attesting Officer Commissioner of Patents 

1. A POLYMERIC COMPOSITION COMPRISING: (A) A POLYMER SELECTED FROM THE GROUP CONSISTING OF POLYOLEFINS, POLYAMIDES, AND POLYSTYRENES; AND (B) 0.5 TO 15 PARTS BY WEIGHT PER 100 PARTS BY WEIGHT OF SAID POLYMER OF A COMPOUND HAVING THE GENERAL FORMULA 